Papermaking machines typically include three main sections: Forming, pressing and drying. The raw material, called furnish, is largely water, and is converted to sheet form in these three sections. The first section, forming, uses vacuum and other means to remove most of the water. At the same time, the fibers of the sheet are formed into the desired mat. The second section, pressing, removes more water by pressing the sheet between felted rolls. The final section, drying, uses rotating heat transfer drums, also called dryers. These dryers are heated by a heat transfer medium, typically steam. A dryer section usually includes many such dryers arranged in single or multiple tiers. The sheet is threaded through this arrangement of dryers, being heated by the rotating dryers so that most or all of the remaining water is evaporated from the sheet.
Steam introduced into each dryers' cylinder condenses as it cools, and the condensate collects on the inside wall of the cylinder. A siphon system is employed to remove this condensate. The siphon system essentially defines a condensate outlet conduit extending from an inlet end positioned close to the interior surface of the cylinder's inside wall, through and out the dryer's journal and to fixed piping beyond.
In order to allow the siphon system to be inserted into a dryer's cylinder through the narrow passageway defined in the journal and still have the end of the siphon system positioned close to the inside surface of the dryer cylinder, siphon systems typically comprise three main components: A horizontal siphon pipe, so named because it is oriented generally horizontally within the dryer, a vertical siphon pipe, so named because, when deployed in the dryer, it extends at an angle in the vertical plane defined relative to the horizontal siphon pipe, and a siphon elbow which interconnects the two siphon pipes in fluid communication. The siphon elbow is generally comprised of fixed and pivoting components, the pivoting components allowing the vertical siphon pipe to be selectively pivoted between a position where it is longitudinal alignment with the horizontal siphon pipe so that the siphon system can be passed through the passageway in the dryer's journal, and a position where the vertical siphon pipe is oriented at an angle relative to the horizontal siphon pipe so that the inlet end is disposed closer to the dryer cylinder's interior surface.
Previously, siphon elbows made use of pivot pins to connect the fixed and pivoting components thereof. These pivot pins tended to shear or break due to the forces imposed on the elbow during installation, service, or in operation of the dryer.